Because of their unique sieving characteristics as well as their catalytic properties, crystalline molecular sieves and zeolites are especially useful in applications such as hydrocarbon conversion, gas drying and separation.
Molecular sieves identified by the International Zeolite Association as having the framework type MTW are known. Examples of MTW framework type materials include CZH-5, NU-13, Theta-3, TPZ-12, and ZSM-12. MTW framework type materials have a one-dimensional pore system with 12-membered rings.
U.K. Patent Application No. 2,079,735 discloses CZH-5 and its synthesis using choline as a structure directing agent.
U.S. Pat. No. 4,743,437 discloses NU-13 and its synthesis in the presence of a piperazine compound as a structure directing agent.
European Patent Application No. 162,719 discloses Theta-3 and its synthesis in the presence of a quaternary nitrogen compound of formula BzNR3+X− where Bz is a benzyl radical, R is hydrocarbyl group and X− is an anion.
U.S. Pat. No. 4,557,919 discloses TPZ-12 and its synthesis in the presence of a pyrrolidine- or piperidine-containing diammonium compound as a structure directing agent.
ZSM-12 and its conventional preparation in the presence of a tetramethylammonium or tetraethylammonium structure directing agent are disclosed in U.S. Pat. No. 3,832,449.
U.S. Pat. No. 4,391,785 discloses a method for the synthesis of ZSM-12 from a reaction mixture comprising, as a structure directing agent, a compound selected from the group consisting of a dimethylpyridinium halide and a dimethylpyrrolidinium halide.
U.S. Pat. Nos. 4,452,769 and 4,537,758 disclose methods for synthesizing ZSM-12 from a reaction mixture containing methyltriethylammonium cations as the structure directing agent.
Other structure directing agents that have been used to synthesize ZSM-12 include DABCO-Cn-diquat cations where n=4, 5, 6 or 10 (see U.S. Pat. No. 4,482,531), bis(dimethylpiperidinium)trimethylene cations (see U.S. Pat. No. 4,539,193), benzyltriethylammonium cations (see U.S. Pat. No. 4,552,738), dibenzyldimethylammonium cations (see U.S. Pat. No. 4,636,373), dimethyldiethylammonium cations (see U.S. Pat. No. 4,552,739), benzyltrimethylammonium cations (see U.S. Pat. No. 4,585,637), bis(N-methylpyridyl)ethylinium cations (see U.S. Pat. No. 4,585,746), hexamethyleneimine (U.S. Pat. No. 5,021,141), decamethonium cations (see U.S. Pat. No. 5,192,521), bis(methylpyrrolidinium) diquat-n ions where n=4, 5, or 6 (see U.S. Pat. No. 5,137,705), and 1,6-bis(2,3-dimethylimidazolium)hexane dications (see U.S. Pat. No. 8,679,451).
According to the present disclosure, MTW framework type molecular sieves have now been synthesized using 1,1-diethyl-4-methylpiperidinium cations as a structure directing agent, and, in some cases, it has been found that small crystal forms of the molecular sieve can be produced.